Chain tightener



13 1953 .1. w. BLISS ETAL CHAIN TIGHTENER 2 Sheets-Sheet 1 Filed March 6, 1958 INKENTORS Dec. 24, 1963 J. w. Buss ETAL CHAIN TIGHTENER 2 Sheets-Sheet 2 Filed March 6, 1958 am 3 w 7 lllllllllllll l E? Viv INVENTORS United States Patent 3,115,046 CHAIN TIGHTENER John W. Bliss and Bernard J. Schill, Rockford, 111.,

assignors to J. I. Case Company, Racine, Wis., a corporation of Wisconsin Filed Mar. 6, 1958, Ser. No. 719,644 2 Claims. (Ci. 74--242.11)

This invention relates to chain drives and specifically to the means for maintaining a constant tension on the chain so as to avoid frequent adjustments, in addition to means to support a chain guard.

When chains employed in chain-and-sprocket drives develop slack they are apt to wear excessively and may then be thrown from the sprockets by vibration. The slack may not be sufficient to permit the removal of an entire link, so a device of the nature of this invention is necessary.

An object of this invention is to provide a device that will maintain a substantially-constant tension on the chain.

Another object is to provide a device that is constantly responsive to changes in the tension of a drive chain caused by wear.

Another object is to provide a device that will provide support for a chain guard and maintain the guard in proper relation to the chain.

Further objects and advantages of the invention will become apparent from a consideration of the following detailed description taken in connection with the accompanying drawings wherein a satisfactory embodiment of the invention is shown. However, it is to be understood the invention is not limited to the details disclosed but includes all such variations and modifications as fall within the spirit of the invention.

Referring to the drawings, FIG. 1, shows a fragmentary side view of a speed drill partly in section, embracing the invention in a preferred form.

FIG. 2, shows an enlarged fragmentary side elevational view of a portion of FIG. 1, partly in section and limited largely to the actual invention.

FIG. 3, is a section taken at 33 of FIG. 2.

FIG. 4, is a section taken at 4-4 of FIG. 2.

Referring again to FIG. 1, drill comprises a frame 12 adapted to be transported, and having a plurality of rearwardly extending arms 14 only one of which is shown. Ann 14, is integrally secured forwardly to frame 12 as at 16. The rearwardly extending portion of frame 12 has secured thereto a depending bracket 18 which is secured at the lower end thereof to the arm 14. Thus arm 14 is an integral part of frame 12.

A press-wheel shaft 20 is journalled below arm 14 in a bearing member 22, supported by brackets 24. A plurality of press wheels 26, only one of which is shown, are secured to shaft 20 so that upon being drawn over the ground, wheels 26 rotate and turn shaft 29. A sprocket 28 is fixed on shaft 20 and spaced axially from bearing 22.

A chain shield 30 is formed so as to embrace both sides of sprocket 28 and extends forwardly toward frame 12. A panel 32 is positioned on one side of sprocket 28 and panel 34 is positioned on the other side of the sprocket. Panels 32 and 34 are joined to an upper panel 36, thus providing a U-shaped shield. Shaft 20 passes through panels 32 and 34 and the shield 30 is journalled on shaft 24) by means of bearings 38 having a pair of lugs 40: Thus shield 31) is provided with means to pivot freely relative to frame 12 about the axis of shaft 20.

A reinforcing member 41 is provided which fits within the forward portion of shield 30 as shown in FIGS. 1,

3,115,046 Patented Dec. 24, 1963 through 3. Bolts 42 and 44 pass through shield 30 and member 41 and secure these members together.

A driven shaft 46 is journalled on frame 12, forwardly of shaft 21), in brackets 48, one of which is shown. A sprocket 50 is keyed to shaft 46.

A chain 52 is trained over sprockets 28 and 50 so that transportation of drill 1i. over the ground will cause shaft 46 to be rotated. Chain 52 is provided with some slack for reasons that will appear from the following description.

An inspection of FIGS. 1 and 2 indicates that the lower run of chain 52 is normally taut when the drill is being operated. The upper run of chain 52 has sufficient slack so as to be trained over a pair of idler blocks 54 and 56 as shown in FIGS. 1 and 2. These blocks are of lubricant impregnated wood such as maple. Block 54 is freely pivoted on a bushing 58 which is supported by a bolt or pivot member 60 which passes through member 41 and shield 30. Block 56 is similarly mounted. Other details of the mounting of blocks 54 and 56 will be specifically described, later.

Idler arms 62 and 64 are positioned one on each side of chain shield 30, parallel thereto, and freely pivoted on bushing 58 as shown in FIGS. 2 and 3. The upper ends of arms 62 and 64 are made integral by a bolt 66 passing through both arms. A nut 68 abuts the inside of arm 64 and nut 70 secures bolt 66 axially.

Washers '72 and 74 are placed on bushing 58 intermediate shield 30 and arms 62 and 64 to prevent friction between the shield and the arms. Bushing 58 is of a length suflicient to permit arms 62 and 64 to pivot freely when nuts 76 and 78 are tightened. Washers 8t) and 82 provide a surface against which nuts 76 and 73 rests, and an abutment for arms 62 and 64.

A spacer bushing 84 is inserted between the webs of member 41 as shown in FIG. 3, and a bolt 86 passes through shield 30, member 41 and bushing 84. A nut 88 secures these members integrally.

Block 56 is pivoted forwardly of block 54 intermediate arms 62 and 64, and above chain 52, as shown in FIGS. 2 and 4. A bushing 90 provides a journal on which block 56 pivots and is of a length sufficient to extend slightly beyond the surfaces of arms 62 and 64. Washers 92 and 94 and a nut 96 serve to secure block 56 in assembly with arms 62 and 64. Bolt 66 is passed through arms 62 and 64 at the upper ends and is provided with a diametrical hole through which a cotter $8 is passed and secured as shown in FIGS. 2 and 3. A tension spring 100 is anchored to bracket 102, which in turn is bolted to frame 12 as shown in FIG. 1.

Chain 52, as before mentioned is trained over sprockets 28 and 50. The upper run of chain 52 is also trained over block 54, the latter in this instance having a guide groove 104 to maintain chain 52 centrally. Chain 52 is also trained under block 56 as shown in FIGS. 1 through 4.

Chain 52 is initially of a length that, when trained over sprockets 28 and Si), and blocks 54 and 56, the arms 62 and 64 will assume the approximate position shown in FIGS. 1 and 2; the assembly of shield 30, chain 52, blocks 54 and 56 and arms 62 and 64 being resiliently supported by spring 100, the position of the assembly depending on the amount of slack in chain 52. Thus it is clear that chain 52 will be maintained in a constant tension. Any wear that takes place in the several parts of this assembly will be compensated for by the forces stored up in spring 100, without requiring frequent adjustment. It is clear that no guard is needed to prevent chain 52 from contacting the front edge of shield 30, in that clearance between the chain and shield is kept constant.

The above being a complete description of an illus- 3 trative embodiment of the invention, what is claimed as new and desired to be secured by Letters Patent of the United States is:

1. In an implement of the class described, having a frame, a drive shaft and a driven shaft journalled thereon, said shafts having aflixed thereto, respectively, a driven sprocket and a driven sprocket in alignment, and a drive chain having an upper run and being trained over said sprockets and having slack, in combination, a chain shield journalled on said drive shaft having the front end thereof swingable relative to said frame and having a panel on each side of said drive sprocket and extending toward said frame, a pair of idler arms pivoted on a transverse pivot on said shield, one of said arms being positioned outwardly of each of said panels and having a forward and rearward extension, a first idler block pivoted on said transverse pivot intermediate said panels and bearing against the underside of said upper run of said chain, a second idler block spaced forwardly and pivoted on said forward extension and intermediate said arms, and bearing on the upper surface of said upper run, and a tension spring anchored between said frame and said rearward extensions to bias said second idler block against said chain to take up said slack.

2. In an implement of the class described, having a frame, a drive shaft and a driven shaft journalled thereon, said shafts having afiixed thereto, respectively, a drive sprocket and a driven sprocket in alignment, and

a drive chain having slack and trained over said sprockets and having an upper run, a chain shield pivotally supported on said drive shaft and having the front end thereof swingable about said shaft relative to said frame, and having a vertical wall on each side of said drive sprocket and extending toward said frame, a pair of idler arms pivoted on a transverse pivot on said shield, one of said arms being positioned outwardly of each of said walls and having a forward and rearward extension, a first idler block pivoted on said transverse pivot interediate said walls and bearing against the underside of said upper run, a second idler block pivoted on said forward extension intermediate said arms and bearing on the upper surface of said upper run, transverse means securing said rearward extensions unitarily, and resilient means anchored between said frame and said transverse means to bias said second idler block against said chain to reduce said slack.

References Cited in the file of this patent UNITED STATES PATENTS 2,563,172 Hyland et a1 Aug. 7, 1951 2,723,566 Hyman Nov. 15, 1955 OTHER REFERENCES Publication: John Deere Operators Manual OM- M 13-153, Van Brunt Model LZ Lister Drill, page 44 relied upon. 

2. IN AN IMPLEMENT OF THE CLASS DESCRIBED, HAVING A FRAME, A DRIVE SHAFT AND A DRIVEN SHAFT JOURNALLED THEREON, SAID SHAFTS HAVING AFFIXED THERETO, RESPECTIVELY, A DRIVE SPROCKET AND A DRIVEN SPROCKET IN ALIGNMENT, AND A DRIVE CHAIN HAVING SLACK AND TRAINED OVER SAID SPROCKETS AND HAVING AN UPPER RUN, A CHAIN SHIELD PIVOTALLY SUPPORTED ON SAID DRIVE SHAFT AND HAVING THE FRONT END THEREOF SWINGABLE ABOUT SAID SHAFT RELATIVE TO SAID FRAME, AND HAVING A VERTICAL WALL ON EACH SIDE OF SAID DRIVE SPROCKET AND EXTENDING TOWARD SAID FRAME, A PAIR OF IDLER ARMS PIVOTED ON A TRANSVERSE PIVOT ON SAID SHIELD, ONE OF SAID ARMS BEING POSITIONED OUTWARDLY OF EACH OF SAID WALLS AND HAVING A FORWARD AND REARWARD EXTENSION, A FIRST IDLER BLOCK PIVOTED ON SAID TRANSVERSE PIVOT INTERMEDIATE SAID WALLS AND BEARING AGAINST THE UNDERSIDE OF SAID UPPER RUN, A SECOND IDLER BLOCK PIVOTED ON SAID FORWARD EXTENSION INTERMEDIATE SAID ARMS AND BEARING ON THE UPPER SURFACE OF SAID UPPER RUN, TRANSVERSE MEANS SECURING SAID REARWARD EXTENSIONS UNITARILY, AND RESILIENT MEANS ANCHORED BETWEEN SAID FRAME AND SAID TRANSVERSE MEANS TO BIAS SAID SECOND IDLER BLOCK AGAINST SAID CHAIN TO REDUCE SAID SLACK. 